1. Technical Field
The present invention relate generally to a fluorescence sensing system, and more particularly, to a system including a polymeric surface having metallic particles deposited thereon and method of forming such metallizable polymeric surfaces.
2. Description of Related Art
Fluorescence systems have become a dominant technology in medical testing, drug discovery, biotechnology and cellular imaging. The use of fluorescence technology has greatly enhanced the ability to detect specific molecules leading to rapid advancements in diagnostics. For example, fluorescence detection is widely used in medical testing and DNA analysis because of the high degree of sensitivity obtained using fluorescent techniques. Importantly a small numbers of molecules can be detected using fluorescence technology. Typically, extrinsic fluorophores are added covalently or non-covalently to allow molecules that do not ordinarily fluoresce or do not fluoresce at useful levels to be detected.
Detection of the molecule of interest is generally limited by the properties of the fluorophore used. In some cases, labeling a biomolecule with an extrinsic fluorophore can alter the biological activity of the biomolecule potentially creating experimental artifacts. Problems with current fluorescent techniques stem in part from the low fluorescent intensities of commonly used fluorophores. Additionally, background fluorescence can be significant when using low wavelength excitation radiation required by some fluorophores or when large quantities of fluorophores are required.
At present, the use of noble metals, particles, and surfaces for applications in sensing, biotechnology, and nanotechnology has drawn considerable attention. For example, U.S. application Ser. No. 10/073,625, discloses compositions and methods for increasing fluorescence intensity of molecules by adding either intrinsic or extrinsic fluorophores, and positioning same at a specific distance from a metal particle. Specifically, metal particles, deposited on glass or quartz type material, and biomolecules with a fluorophore are positioned at a distance from the metal particles. This positioning of the fluorophore at a specific distance from the metal particle can alter or increase the intrinsic emission of electromagnetic radiation from the biomolecule in response to an amount of exciting electromagnetic radiation.
Favorable effects of silver particles on fluorophores include increased quantum yields, decreased lifetimes, and increased photostability of fluorophores commonly used in biological research. These effects of conducting metallic particles on fluorescence have been the subject of numerous theoretical studies related to surface-enhanced Raman scattering and the application of these considerations to molecular fluorescence. There is now interest in using the remarkable properties of metallic islands, colloids or continuous surfaces.
Consequently, it is of interest to develop convenient methods for forming metallic particles and/or films on different surfaces. These approaches include electroless deposition, electroplating on insulators, lithography, and the formation of colloids under constant reagent flow. Metallic particles can be assembled into films using electrophoresis, and gold particles have been used for the on-demand electrochemical release of DNA. It is anticipated that many of these approaches will find uses in medical diagnostics and lab-on-a-chip-type applications.
Heretofore, all of these findings have been based on metallic silver being deposited on glass or quartz type substrates with a subsequent spacer layer used to separate the fluorophore from the metal. Thus, it would be of great value to devise methods for localized or continuous silver deposition on other surfaces that are more flexible that glass planar surfaces or glass-based substrates.